Volume control and switching device



H. LISSAUER VOLUME CONTROL AND SWITCHING DEVICE Filed April 11, 1932 INVENTOR HERBERT us um BY I 5 M ATTORNEY Patented Apr. 28, 1936 UNITED STATES VOLUME CONTROL AND SWITCHING DEVICE Herbert Lissauer, Berlin,

Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany 7 Application April 11, 19

32, Serial No. 604,596

In Germany May 5, 1931 An object of my invention is to provide a novel type of volume control and switching device and more especially one which is adapted for use with a radio receiver and electrical phonograph.

A further object is to provide such a device in which the operation is simplified by the control of two separate volume control means from a single operating handle or knob.

A still further object is to control the input voltage impressed on the grid of an amplifier tube from either of two voltage sources by the operation of a single control member or knob.

Other objects of the invention will become evident as the description thereof proceeds in con nection with the following specification. A specific embodiment of the invention is shown in the accompanying drawing in which,

Fig. 1 is a diagrammatic circuit arrangement of an amplifier showing the switches and variable elements used to control the amplification; and,

Fig. 2 is a perspective view of the operating shaft and volume control elements.

In thermionic tube amplifiers which may be connected with phonographs or to a broadcast receiver the output volume or current as a rule for both of the said modes of operation is regulated in different ways and by various elements or means.

According to the present invention, manipulation and operation of the equipment is substantially simplified by that arrangements are made so that one and the same operating handle or knob inside part of its range of setting or adjustment (for instance, its angle of rotation) actuates and controls the regulating means for adjustment of the ultimate volume in audio frequency recep tion or reproduction and inside the other part or remainder of its range of adjustment the regulation of output volume or current for broadcast reception, while during the change from one setting range to the other the changes in circuit, etc. from radio reception to tonal reception are eifected. Another improvement of the operating means consists in that the handle or knob designed to insure the selective change to the one or the other form of working as well as the regulation of the volume, upon passing through the intermediate position between the said two ranges of control or adjustment, disconnects the power or service switch of the receiver while re-closing the same upon this position being left.

In what follows the essential features of the arrangement of this invention shall be explained in more detail by reference to the drawing.

Fig. 1 illustrates a circuit arrangement for the 7 Claims.

input stage of the amplifier adapted to be connected at will for broadcast reception or for phonograph operation. The input or vacuum tube amplifier B of the receiver may be fed from the power network by way of a service switch H and a rectifier and filter unit G, when the switch U is opened, is connected for broadcast reception, the grid circuit thereof being energized from the oscillation circuit LC being coupled with aerial A. For radio reception LC may be tuned to the incoming signal frequency. The volume is regulated by means of a variable condenser R included in the regenerative or feed-back circuit in which coil M is preferably inductively coupled to coil L. To effect the change tophonograph 1 operation the switch U is closed with the result that the circuit of the electromagnetic pick-up coil S of the phonograph is connected in the grid circuit of tube B. The change-over switch U could also be so designed that simultaneously with the making of the pick-up circuit of the phonograph, the R. F. oscillation circuit LC is disconnected. However, as a rule this is'unnecessary inasmuch as the cutting in circuit of parallel resistance W renders R. F. reception impossible or ineffective. 25 The regulation of the end volume in phonograph working is effected by the setting of parallel resistance W which may be about 20,000 ohms and is much lower than impedance K which may be 1 megohm.

, Hence, in this scheme, according to the invention, the simplification here aimed at would reside in thatthe actuation of change-over switch U and of the regulating means W and R and optionally also of the service or power switch H would 35 be accomplished by one and the same actuating knob.

An embodiment of such a change-over and regulating device according to this invention is illustrated by way of example in Fig. 2. The op- 40 crating knob D, on the one hand, controls the rotor plates 1' mounted upon' this spindle and cooperating with the stator 3 both belonging to the feed back condenser R serving for controlling the volume in radio reception, and, on the other, 45 it actuates the contact slide 10 movable over resistance W and serving for regulation of the volume in phonograph operating. To effect a change-over to phonograph operation there are used here the brushes U adapted to cooperate so with suitable contact segments 20 connected to terminals l and 2, one end of resistor W being connected to terminal 3, as shown.

In the zero position of pointer E, as shown in Fig. 2, the service switch H of the apparatus is 55 opened by a cam h. 7 Upon adjusting the pointer of the knob into the left-hand range of rotation the service switch H is closed, the change-over switch U remains opened, and the amplifier is connected for broadcast reception, the volume being regulated by the adjustment of the regenerative control condenser R. In the lowermost position of the knob and itspointer the apparatus is again disconnected by the opening of the service switch H by cam it. As the control knob is further rotated the switch H is re-closed and when pointer E is inside the right-hand range the change-over switch U is closed; in other words, the amplifier is changed over to phonograph operation and regulation of volume is effected by contact w sliding on the parallel resistance W.

As shown, shaft F may be metallic in'which case the central section I is insulated from end section 8 which carries arm 9 on which slide w is mounted by an insulationg collar I ll. A similar insulating collar ll connects the section I and the end section l2 which carries cam h. As shown, the switch H may be open for a motion of the pointer E of 5 degrees to the left of its zero or vertical position, during the next 170 degrees of its motion the volume level or plate current of B is adjusted to the desired value by condenser R and during the next 5 degrees of its motion to the downward position the power switch H is again opened. In otherwords, a motion of about degrees to the left of its vertical position of E is available to control the volume of the radio receiver and a similar degree of rotation thereof to the right is available to control the output volume level of the phonograph. However, my invention is not limited to the specific angular relations mentioned by way of example only; nor is it limited to mounting the rotor plates 1' and arm 9 on the same shaft as they may be connected together for joint or uni-control operation by many well known mechanical equivalents thereof. The output terminals l5 and I6 may be connected to another vacuum tube amplifier for further amplification or to a sound reproducer such as a telephone receiver or loudspeaker. It will be understood that for the modulated radio frequency incoming signals, tube B may be operated as a regenerative detector and amplifier to detect the audio frequency signal component. The turntable l1, stylus I8 and other operating parts of the electric phonograph may be of the usual construction and no further description thereof is necessary.

Having described my invention, what I claim by Letters Patent is:

1. In a device of the class described, a'vacuum tube amplifier having an input and an output circuit, means for adjustably coupling said circuits to, provide a feedback connection therebetween, a

source o-f'lowfrequency currents, means for controlling the voltage impressed on the input circuit of said amplifier by said source and a common' operating means adjustable over, a large range of movement arranged to operate'said adjustable coupling means over a portion of said range and to selectively operate said controlling.

means over a different portion of its range of. movement.

2. In a device of the class described, an amplifier having a tunable input circuit, an adjustable condenser for tuning said circuit to incoming radio signals, an adjustable impedance connected to said circuit, a switching device conductively connected in said input circuit between said impedance and said amplifier and a' single control means connected to adjust said impedance and to operate said switching device to connect and disconnect said impedance across the input circuit.

'to adjust said contact along said impedance and operate said switching device.

4. In combination, a vacuum tube amplifier having grid and plate circuits, means for feeding energy from said plate to said grid circuit including a variable condenser, a source of audio frequency currents, an impedance connected thereto, a contact adjustable along said impedance, connections between said impedance and the grid circuit of said tube, and a common operating shaft connected to said variable condenser and said adjustable contact.

5. In combination, a vacuum tube amplifier having a cathode, grid and plate, a resonant circuit connecting said grid and cathode, a feed back connection between the plate and said resonant circuit including a condenser having at least one rotor plate, a source of audio frequency having at least two sections, insulating means connecting said sections, a contact arm adjustable along said impedance connected to one of said shaft sections, the rotor plate of said condenser being carried by the other shaft section, a connection between one end of said impedance and said cathode and a. connection between said contact arm and said grid.

6. In combination, a vacuum tube amplifier having a grid circuit and a plate circuit, a variable impedance having a rotor portion connected to provide a feedback between said plate and grid circuits, an operating shaft having an insulated portion and an end portion, said rotor portion being mounted on said insulated shaft portion, a

resistor and a pair of conductive members, a brush bination of a shaft having three insulated sections, a vacuum tube having an input circuit, a reactance having an adjustable portion mounted on a first section of said shaft; a resistor cone. ductively connected to saidinputcircuit and having a contact adjustable therealong, said contact being mounted on a second section of said shaft} power supply means for energizing said vacuum;

tube, a switch arrangedto shut off the current tosaid power supply and having a movable blade and a member mounted on the third shaft section arranged to operate said movable switch blade.

HERBERT LISSAUER. 

